←API Reference ←com.nianticspatial.nsdk.utils

ImageMath

Kotlin wrapper for ARDK ImageMath functions. Each function returns an [android.graphics.Matrix] corresponding to a 3×3 affine or projective transformation.

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Declaration

object ImageMath

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Functions

Name	Type	Summary
affineCrop	Matrix	Returns an affine transformation that crops the source size to match the aspect ratio of the target size.
affineFit	Matrix	Returns an affine transformation that maps normalized coordinates in the source frame to normalized coordinates in the target frame.
affineInvertHorizontal	Matrix	Returns an affine matrix for horizontal mirroring. Maps (u, v) → (1 - u, v).
affineInvertVertical	Matrix	Returns an affine matrix for vertical mirroring. Maps (u, v) → (u, 1 - v).
affineRotation	Matrix	Returns an (u, v) -> (u', v') transformation that represents a 2D affine rotation.
affineScaling	Matrix	Returns an (u, v) -> (u', v') transformation that represents a 2D affine scaling.
affineTranslation	Matrix	Returns an (u, v) -> (u', v') transformation that represents a 2D affine translation.
calculateDeviceRotation	Matrix	Returns an affine transform that rotates between two interface orientations around the center. This method models physical device rotation.
calculateViewRotation	Matrix	Returns an affine transform that rotates between two interface orientations around the center. This method models UI rotation (opposite to physical device rotation).
concatenating	Matrix	Returns a new [Matrix] representing the concatenation of this matrix with another matrix, mimicking the behavior of CoreGraphics’ concatenating(_:) method on iOS.
displayTransform	Matrix	Returns an affine transform [Matrix] that maps normalized image coordinates into a coordinate space suitable for rendering the camera image in the given viewport and orientation.
logAffine	void	Logs the affine components of this [Matrix] in a readable format. Prints the matrix in iOS-style notation: a, b, c, d, tx, ty corresponding to the 2×3 affine transform: [ a c tx ] [ b d ty ]
logMatrix	void	Logs the contents of this [Matrix] as a 3×3 matrix. The matrix values are printed in row-major order, as used internally by [android.graphics.Matrix]. Useful for debugging transformations like scale, rotation, skew, and perspective.
reprojection	Matrix	Returns a 3×3 homography matrix (android.graphics.Matrix) that reprojects image coordinates from a reference camera view into a target camera view. This is typically used to transform 2D image-space coordinates (normalized in [0..1]) from one camera perspective to another, e.g. for aligning visual overlays between AR frames.
reprojectPoints	void	Applies a full 3×3 projective transformation (homography) to a set of 2D points, using this [Matrix] as a homography matrix. Unlike [Matrix.mapPoints], this method correctly applies the bottom row of the matrix and performs the required perspective divide. Transformed points are clamped to the [-1f..2f] range to ensure compatibility with UI constraints.

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